# ilogbl(3) [netbsd man page]

ILOGB(3) BSD Library Functions Manual ILOGB(3)NAME

ilogb, ilogbf, ilogblan unbiased exponent--LIBRARY

Math Library (libm, -lm)SYNOPSIS

#include <math.h> int ilogb(double x); int ilogbf(float x); int ilogbl(long double x);DESCRIPTION

The ilogb(), ilogbf(), and ilogbl() functions return the exponent of the non-zero real floating-point number x as a signed integer value. Formally the return value is the integral part of log_r | x |, where r is the radix of the machine's floating-point arithmetic defined by the FLT_RADIX constant in <float.h>.RETURN VALUES

As described above, upon successful completion, the functions return the exponent. Functionally this is the same as calling the correspond- ing logb(3) function and casting the return value to int. The following special cases may occur: 1. If x is zero, the value of FP_ILOGB0 is returned and a domain error occurs. 2. If x is infinite, a domain error occurs and the value of INT_MAX is returned. 3. If x is NaN, a domain error is raised and the value of FP_ILOGBNAN is returned. 4. If the correct value is outside the range of the return type, a domain error occurs but an unspecified value is returned.SEE ALSO

ilog2(3), logb(3), math(3)STANDARDS

The described functions conform to ISO/IEC 9899:1999 (``ISO C99'').BUGS

Neither FP_ILOGB0 nor FP_ILOGBNAN is defined currently in NetBSD.BSD

July 29, 2011 BSD

## Check Out this Related Man Page

NAME

ilogb, ilogbf, ilogblan unbiased exponent--LIBRARY

Math Library (libm, -lm)SYNOPSIS

#include <math.h> int ilogb(double x); int ilogbf(float x); int ilogbl(long double x);DESCRIPTION

The ilogb(), ilogbf(), and ilogbl() functions return the exponent of the non-zero real floating-point number x as a signed integer value. Formally the return value is the integral part of log_r | x |, where r is the radix of the machine's floating-point arithmetic defined by the FLT_RADIX constant in <float.h>.RETURN VALUES

As described above, upon successful completion, the functions return the exponent. Functionally this is the same as calling the correspond- ing logb(3) function and casting the return value to int. The following special cases may occur: 1. If x is zero, the value of FP_ILOGB0 is returned and a domain error occurs. 2. If x is infinite, a domain error occurs and the value of INT_MAX is returned. 3. If x is NaN, a domain error is raised and the value of FP_ILOGBNAN is returned. 4. If the correct value is outside the range of the return type, a domain error occurs but an unspecified value is returned.SEE ALSO

ilog2(3), logb(3), math(3)STANDARDS

The described functions conform to ISO/IEC 9899:1999 (``ISO C99'').BUGS

Neither FP_ILOGB0 nor FP_ILOGBNAN is defined currently in NetBSD.BSD

July 29, 2011 BSD